The present invention is directed to equipment for the processing of solid particulate materials to effect heat exchange. Most typically, the system is employed in the cooling of solid particulate materials during production processing.
It is known in the construction of heat exchange processors to employ hydrostatically expanded heat exchange panels within a heat exchange vessel, for the evaporation and concentration of liquids, for example. Such heat exchange panels are constructed by joining together a pair of sheet metal plates by welding the plates together around their peripheral edges to form a fluid tight enclosure. The facing sheets of metal are then secured together in limited areas of joinder, typically by spot welding. These areas are arranged in a predetermined uniform pattern over the entire flat surface area of the panel. For example, the areas of joinder may be a half to three quarters inch in diameter, spaced apart on, for example, four inch centers. Each panel is provided with a fluid inlet and a fluid outlet substantially spaced from each other, typically at diagonally opposite corners of the panel. The thus prepared panels are then hydrostatically expanded by forcing fluid under relatively high pressure into the interior of the panel, preferably but not necessarily while the areas of joinder are mechanically clamped together. The panel areas between the areas of joinder are permanently deformed outwardly from the central plane of the panel to provide labyrinthine internal passages for the flow of heat exchange medium inside the panel.
Heat exchange panels of the type described above are generally known. The present invention provides a unique and advantageous way of employing such panels in a heat exchange system for the processing of solid particulate material in a way to greatly increase the efficiency of the heat exchange process for such material.
In accordance with the invention, a heat exchanger system is provided which includes a heat exchange housing provided with an inlet and an outlet for flowing particulate solids. Typically, the system operates by gravity flow, with the heat exchange housing being vertically oriented, with its inlet at the top and its outlet at the bottom. The heat exchange housing is packed with a series of flat heat exchange panels, of the general type described above, vertically oriented and arranged in parallel, closely spaced relation to define a plurality of vertically oriented narrow flow paths for moving the solid particulate material through the heat exchange housing.
Because of the quilt-like modulating surface contours of the heat exchange panel, "bridging" of the solid particulate material between panels becomes a problem as the spacing between panels is reduced. Inasmuch as the efficiency of the heat exchange operation is a significant function of the spacing between adjacent panels, the efficiency of a given system for a given particulate material can be optimized by reducing the space between adjacent panels as far as possible while avoiding problems of "bridging" of the particulate materials, especially in relatively convergent areas of adjacent, opposed panels.
Pursuant to the invention, a significantly improved and efficient heat exchange system for particulate solids is provided by constructing and arranging the heat exchange panels in such manner that the hydrostatically expanded portions of one panel are positioned directly opposite the areas of joinder of each adjacent panel. This provides, between each pair of panels, a passage of a sinuous character but with significantly greater uniformity of width over the entire surface areas of the plates. By minimizing areas of convergence, an adjacent pair of heat exchange panels may be moved closer together, for greater heat exchange efficiency, without exacerbating the problem of bridging of the particulate solids flowing through the system.
The structure of the invention is advantageously achieved by constructing the panels to be of two types. In a first alternate panel type, the areas of joinder are arranged in a first predetermined pattern. In a second alternate panel type, the configuration of the areas of joinder, is offset such that each area of joinder lies substantially midway between corresponding areas of joinder of the first alternate panels. When a series of alternate types of panels are assembled in a stack, the spacing between panels can be significantly reduced without causing bridging of the solid particulate material. This has two important advantages: First, because adjacent heat exchange panels are closely spaced, there is greater efficiency of heat transfer between the plates and a mass of flowing particulate solid material flowing there between. Secondly, the closer spacing of the panel allows for a greater number of the panels to be assembled in a housing of given size.
For a more complete understanding of the above and other features and advantages of the invention, reference should be made to the following detailed description of a preferred embodiment of the invention and to the accompanying drawings.